/* pngwtran.c - transforms the data in a row for PNG writers

  libpng version 1.2.7 - September 12, 2004
  For conditions of distribution and use, see copyright notice in png.h
  Copyright (c) 1998-2004 Glenn Randers-Pehrson
  (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
  (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
*/

#define PNG_INTERNAL
#include "png.h"
#ifdef PNG_WRITE_SUPPORTED

/* Transform the data according to the user's wishes.  The order of
  transformations is significant.
*/
void /* PRIVATE */
png_do_write_transformations( png_structp png_ptr ) {
  png_debug( 1, "in png_do_write_transformations\n" );
  if( png_ptr == NULL ) {
    return;
  }
  #if defined(PNG_WRITE_USER_TRANSFORM_SUPPORTED)
  if( png_ptr->transformations & PNG_USER_TRANSFORM )
    if( png_ptr->write_user_transform_fn != NULL )
      ( *( png_ptr->write_user_transform_fn ) ) /* user write transform function */
      ( png_ptr,                   /* png_ptr */
        & ( png_ptr->row_info ),    /* row_info:     */
        /*  png_uint_32 width;          width of row */
        /*  png_uint_32 rowbytes;       number of bytes in row */
        /*  png_byte color_type;        color type of pixels */
        /*  png_byte bit_depth;         bit depth of samples */
        /*  png_byte channels;          number of channels (1-4) */
        /*  png_byte pixel_depth;       bits per pixel (depth*channels) */
        png_ptr->row_buf + 1 );     /* start of pixel data for row */
  #endif
  #if defined(PNG_WRITE_FILLER_SUPPORTED)
  if( png_ptr->transformations & PNG_FILLER )
    png_do_strip_filler( &( png_ptr->row_info ), png_ptr->row_buf + 1,
                         png_ptr->flags );
  #endif
  #if defined(PNG_WRITE_PACKSWAP_SUPPORTED)
  if( png_ptr->transformations & PNG_PACKSWAP ) {
    png_do_packswap( &( png_ptr->row_info ), png_ptr->row_buf + 1 );
  }
  #endif
  #if defined(PNG_WRITE_PACK_SUPPORTED)
  if( png_ptr->transformations & PNG_PACK )
    png_do_pack( &( png_ptr->row_info ), png_ptr->row_buf + 1,
                 ( png_uint_32 )png_ptr->bit_depth );
  #endif
  #if defined(PNG_WRITE_SWAP_SUPPORTED)
  if( png_ptr->transformations & PNG_SWAP_BYTES ) {
    png_do_swap( &( png_ptr->row_info ), png_ptr->row_buf + 1 );
  }
  #endif
  #if defined(PNG_WRITE_SHIFT_SUPPORTED)
  if( png_ptr->transformations & PNG_SHIFT )
    png_do_shift( &( png_ptr->row_info ), png_ptr->row_buf + 1,
                  &( png_ptr->shift ) );
  #endif
  #if defined(PNG_WRITE_INVERT_ALPHA_SUPPORTED)
  if( png_ptr->transformations & PNG_INVERT_ALPHA ) {
    png_do_write_invert_alpha( &( png_ptr->row_info ), png_ptr->row_buf + 1 );
  }
  #endif
  #if defined(PNG_WRITE_SWAP_ALPHA_SUPPORTED)
  if( png_ptr->transformations & PNG_SWAP_ALPHA ) {
    png_do_write_swap_alpha( &( png_ptr->row_info ), png_ptr->row_buf + 1 );
  }
  #endif
  #if defined(PNG_WRITE_BGR_SUPPORTED)
  if( png_ptr->transformations & PNG_BGR ) {
    png_do_bgr( &( png_ptr->row_info ), png_ptr->row_buf + 1 );
  }
  #endif
  #if defined(PNG_WRITE_INVERT_SUPPORTED)
  if( png_ptr->transformations & PNG_INVERT_MONO ) {
    png_do_invert( &( png_ptr->row_info ), png_ptr->row_buf + 1 );
  }
  #endif
}

#if defined(PNG_WRITE_PACK_SUPPORTED)
/* Pack pixels into bytes.  Pass the true bit depth in bit_depth.  The
  row_info bit depth should be 8 (one pixel per byte).  The channels
  should be 1 (this only happens on grayscale and paletted images).
*/
void /* PRIVATE */
png_do_pack( png_row_infop row_info, png_bytep row, png_uint_32 bit_depth ) {
  png_debug( 1, "in png_do_pack\n" );
  if( row_info->bit_depth == 8 &&
    #if defined(PNG_USELESS_TESTS_SUPPORTED)
      row != NULL && row_info != NULL &&
    #endif
      row_info->channels == 1 ) {
    switch( ( int )bit_depth ) {
      case 1: {
        png_bytep sp, dp;
        int mask, v;
        png_uint_32 i;
        png_uint_32 row_width = row_info->width;
        sp = row;
        dp = row;
        mask = 0x80;
        v = 0;
        for( i = 0; i < row_width; i++ ) {
          if( *sp != 0 ) { v |= mask; }
          sp++;
          if( mask > 1 ) { mask >>= 1; }
          else {
            mask = 0x80;
            *dp = ( png_byte )v;
            dp++;
            v = 0;
          }
        }
        if( mask != 0x80 ) { *dp = ( png_byte )v; }
        break;
      }
      case 2: {
        png_bytep sp, dp;
        int shift, v;
        png_uint_32 i;
        png_uint_32 row_width = row_info->width;
        sp = row;
        dp = row;
        shift = 6;
        v = 0;
        for( i = 0; i < row_width; i++ ) {
          png_byte value;
          value = ( png_byte )( *sp & 0x03 );
          v |= ( value << shift );
          if( shift == 0 ) {
            shift = 6;
            *dp = ( png_byte )v;
            dp++;
            v = 0;
          } else
          { shift -= 2; }
          sp++;
        }
        if( shift != 6 ) { *dp = ( png_byte )v; }
        break;
      }
      case 4: {
        png_bytep sp, dp;
        int shift, v;
        png_uint_32 i;
        png_uint_32 row_width = row_info->width;
        sp = row;
        dp = row;
        shift = 4;
        v = 0;
        for( i = 0; i < row_width; i++ ) {
          png_byte value;
          value = ( png_byte )( *sp & 0x0f );
          v |= ( value << shift );
          if( shift == 0 ) {
            shift = 4;
            *dp = ( png_byte )v;
            dp++;
            v = 0;
          } else
          { shift -= 4; }
          sp++;
        }
        if( shift != 4 ) { *dp = ( png_byte )v; }
        break;
      }
    }
    row_info->bit_depth = ( png_byte )bit_depth;
    row_info->pixel_depth = ( png_byte )( bit_depth * row_info->channels );
    row_info->rowbytes = PNG_ROWBYTES( row_info->pixel_depth,
                                       row_info->width );
  }
}
#endif

#if defined(PNG_WRITE_SHIFT_SUPPORTED)
/* Shift pixel values to take advantage of whole range.  Pass the
  true number of bits in bit_depth.  The row should be packed
  according to row_info->bit_depth.  Thus, if you had a row of
  bit depth 4, but the pixels only had values from 0 to 7, you
  would pass 3 as bit_depth, and this routine would translate the
  data to 0 to 15.
*/
void /* PRIVATE */
png_do_shift( png_row_infop row_info, png_bytep row, png_color_8p bit_depth ) {
  png_debug( 1, "in png_do_shift\n" );
  #if defined(PNG_USELESS_TESTS_SUPPORTED)
  if( row != NULL && row_info != NULL &&
  #else
  if(
  #endif
      row_info->color_type != PNG_COLOR_TYPE_PALETTE ) {
    int shift_start[4]
    , shift_dec[4];
    int channels = 0;
    if( row_info->color_type & PNG_COLOR_MASK_COLOR ) {
      shift_start[channels] = row_info->bit_depth - bit_depth->red;
      shift_dec[channels] = bit_depth->red;
      channels++;
      shift_start[channels] = row_info->bit_depth - bit_depth->green;
      shift_dec[channels] = bit_depth->green;
      channels++;
      shift_start[channels] = row_info->bit_depth - bit_depth->blue;
      shift_dec[channels] = bit_depth->blue;
      channels++;
    } else {
      shift_start[channels] = row_info->bit_depth - bit_depth->gray;
      shift_dec[channels] = bit_depth->gray;
      channels++;
    }
    if( row_info->color_type & PNG_COLOR_MASK_ALPHA ) {
      shift_start[channels] = row_info->bit_depth - bit_depth->alpha;
      shift_dec[channels] = bit_depth->alpha;
      channels++;
    }
    /* with low row depths, could only be grayscale, so one channel */
    if( row_info->bit_depth < 8 ) {
      png_bytep bp = row;
      png_uint_32 i;
      png_byte mask;
      png_uint_32 row_bytes = row_info->rowbytes;
      if( bit_depth->gray == 1 && row_info->bit_depth == 2 ) { mask = 0x55; }
      else if( row_info->bit_depth == 4 && bit_depth->gray == 3 ) { mask = 0x11; }
      else
      { mask = 0xff; }
      for( i = 0; i < row_bytes; i++, bp++ ) {
        png_uint_16 v;
        int j;
        v = *bp;
        *bp = 0;
        for( j = shift_start[0]; j > -shift_dec[0]; j -= shift_dec[0] ) {
          if( j > 0 ) { *bp |= ( png_byte )( ( v << j ) & 0xff ); }
          else
          { *bp |= ( png_byte )( ( v >> ( -j ) ) & mask ); }
        }
      }
    } else if( row_info->bit_depth == 8 ) {
      png_bytep bp = row;
      png_uint_32 i;
      png_uint_32 istop = channels * row_info->width;
      for( i = 0; i < istop; i++, bp++ ) {
        png_uint_16 v;
        int j;
        int c = ( int )( i % channels );
        v = *bp;
        *bp = 0;
        for( j = shift_start[c]; j > -shift_dec[c]; j -= shift_dec[c] ) {
          if( j > 0 ) { *bp |= ( png_byte )( ( v << j ) & 0xff ); }
          else
          { *bp |= ( png_byte )( ( v >> ( -j ) ) & 0xff ); }
        }
      }
    } else {
      png_bytep bp;
      png_uint_32 i;
      png_uint_32 istop = channels * row_info->width;
      for( bp = row, i = 0; i < istop; i++ ) {
        int c = ( int )( i % channels );
        png_uint_16 value, v;
        int j;
        v = ( png_uint_16 )( ( ( png_uint_16 )( *bp ) << 8 ) + * ( bp + 1 ) );
        value = 0;
        for( j = shift_start[c]; j > -shift_dec[c]; j -= shift_dec[c] ) {
          if( j > 0 ) { value |= ( png_uint_16 )( ( v << j ) & ( png_uint_16 )0xffff ); }
          else
          { value |= ( png_uint_16 )( ( v >> ( -j ) ) & ( png_uint_16 )0xffff ); }
        }
        *bp++ = ( png_byte )( value >> 8 );
        *bp++ = ( png_byte )( value & 0xff );
      }
    }
  }
}
#endif

#if defined(PNG_WRITE_SWAP_ALPHA_SUPPORTED)
void /* PRIVATE */
png_do_write_swap_alpha( png_row_infop row_info, png_bytep row ) {
  png_debug( 1, "in png_do_write_swap_alpha\n" );
  #if defined(PNG_USELESS_TESTS_SUPPORTED)
  if( row != NULL && row_info != NULL )
  #endif
  {
    if( row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA ) {
      /* This converts from ARGB to RGBA */
      if( row_info->bit_depth == 8 ) {
        png_bytep sp, dp;
        png_uint_32 i;
        png_uint_32 row_width = row_info->width;
        for( i = 0, sp = dp = row; i < row_width; i++ ) {
          png_byte save = *( sp++ );
          *( dp++ ) = *( sp++ );
          *( dp++ ) = *( sp++ );
          *( dp++ ) = *( sp++ );
          *( dp++ ) = save;
        }
      }
      /* This converts from AARRGGBB to RRGGBBAA */
      else {
        png_bytep sp, dp;
        png_uint_32 i;
        png_uint_32 row_width = row_info->width;
        for( i = 0, sp = dp = row; i < row_width; i++ ) {
          png_byte save[2];
          save[0] = *( sp++ );
          save[1] = *( sp++ );
          *( dp++ ) = *( sp++ );
          *( dp++ ) = *( sp++ );
          *( dp++ ) = *( sp++ );
          *( dp++ ) = *( sp++ );
          *( dp++ ) = *( sp++ );
          *( dp++ ) = *( sp++ );
          *( dp++ ) = save[0];
          *( dp++ ) = save[1];
        }
      }
    } else if( row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA ) {
      /* This converts from AG to GA */
      if( row_info->bit_depth == 8 ) {
        png_bytep sp, dp;
        png_uint_32 i;
        png_uint_32 row_width = row_info->width;
        for( i = 0, sp = dp = row; i < row_width; i++ ) {
          png_byte save = *( sp++ );
          *( dp++ ) = *( sp++ );
          *( dp++ ) = save;
        }
      }
      /* This converts from AAGG to GGAA */
      else {
        png_bytep sp, dp;
        png_uint_32 i;
        png_uint_32 row_width = row_info->width;
        for( i = 0, sp = dp = row; i < row_width; i++ ) {
          png_byte save[2];
          save[0] = *( sp++ );
          save[1] = *( sp++ );
          *( dp++ ) = *( sp++ );
          *( dp++ ) = *( sp++ );
          *( dp++ ) = save[0];
          *( dp++ ) = save[1];
        }
      }
    }
  }
}
#endif

#if defined(PNG_WRITE_INVERT_ALPHA_SUPPORTED)
void /* PRIVATE */
png_do_write_invert_alpha( png_row_infop row_info, png_bytep row ) {
  png_debug( 1, "in png_do_write_invert_alpha\n" );
  #if defined(PNG_USELESS_TESTS_SUPPORTED)
  if( row != NULL && row_info != NULL )
  #endif
  {
    if( row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA ) {
      /* This inverts the alpha channel in RGBA */
      if( row_info->bit_depth == 8 ) {
        png_bytep sp, dp;
        png_uint_32 i;
        png_uint_32 row_width = row_info->width;
        for( i = 0, sp = dp = row; i < row_width; i++ ) {
          *( dp++ ) = *( sp++ );
          *( dp++ ) = *( sp++ );
          *( dp++ ) = *( sp++ );
          *( dp++ ) = ( png_byte )( 255 - * ( sp++ ) );
        }
      }
      /* This inverts the alpha channel in RRGGBBAA */
      else {
        png_bytep sp, dp;
        png_uint_32 i;
        png_uint_32 row_width = row_info->width;
        for( i = 0, sp = dp = row; i < row_width; i++ ) {
          *( dp++ ) = *( sp++ );
          *( dp++ ) = *( sp++ );
          *( dp++ ) = *( sp++ );
          *( dp++ ) = *( sp++ );
          *( dp++ ) = *( sp++ );
          *( dp++ ) = *( sp++ );
          *( dp++ ) = ( png_byte )( 255 - * ( sp++ ) );
          *( dp++ ) = ( png_byte )( 255 - * ( sp++ ) );
        }
      }
    } else if( row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA ) {
      /* This inverts the alpha channel in GA */
      if( row_info->bit_depth == 8 ) {
        png_bytep sp, dp;
        png_uint_32 i;
        png_uint_32 row_width = row_info->width;
        for( i = 0, sp = dp = row; i < row_width; i++ ) {
          *( dp++ ) = *( sp++ );
          *( dp++ ) = ( png_byte )( 255 - * ( sp++ ) );
        }
      }
      /* This inverts the alpha channel in GGAA */
      else {
        png_bytep sp, dp;
        png_uint_32 i;
        png_uint_32 row_width = row_info->width;
        for( i = 0, sp = dp = row; i < row_width; i++ ) {
          *( dp++ ) = *( sp++ );
          *( dp++ ) = *( sp++ );
          *( dp++ ) = ( png_byte )( 255 - * ( sp++ ) );
          *( dp++ ) = ( png_byte )( 255 - * ( sp++ ) );
        }
      }
    }
  }
}
#endif

#if defined(PNG_MNG_FEATURES_SUPPORTED)
/* undoes intrapixel differencing  */
void /* PRIVATE */
png_do_write_intrapixel( png_row_infop row_info, png_bytep row ) {
  png_debug( 1, "in png_do_write_intrapixel\n" );
  if(
  #if defined(PNG_USELESS_TESTS_SUPPORTED)
    row != NULL && row_info != NULL &&
  #endif
    ( row_info->color_type & PNG_COLOR_MASK_COLOR ) ) {
    int bytes_per_pixel;
    png_uint_32 row_width = row_info->width;
    if( row_info->bit_depth == 8 ) {
      png_bytep rp;
      png_uint_32 i;
      if( row_info->color_type == PNG_COLOR_TYPE_RGB ) { bytes_per_pixel = 3; }
      else if( row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA ) { bytes_per_pixel = 4; }
      else
      { return; }
      for( i = 0, rp = row; i < row_width; i++, rp += bytes_per_pixel ) {
        *( rp )   = ( png_byte )( ( *rp     - * ( rp + 1 ) ) & 0xff );
        *( rp + 2 ) = ( png_byte )( ( *( rp + 2 ) - * ( rp + 1 ) ) & 0xff );
      }
    } else if( row_info->bit_depth == 16 ) {
      png_bytep rp;
      png_uint_32 i;
      if( row_info->color_type == PNG_COLOR_TYPE_RGB ) { bytes_per_pixel = 6; }
      else if( row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA ) { bytes_per_pixel = 8; }
      else
      { return; }
      for( i = 0, rp = row; i < row_width; i++, rp += bytes_per_pixel ) {
        png_uint_32 s0   = ( *( rp ) << 8 ) | *( rp + 1 );
        png_uint_32 s1   = ( *( rp + 2 ) << 8 ) | *( rp + 3 );
        png_uint_32 s2   = ( *( rp + 4 ) << 8 ) | *( rp + 5 );
        png_uint_32 red  = ( png_uint_32 )( ( s0 - s1 ) & 0xffffL );
        png_uint_32 blue = ( png_uint_32 )( ( s2 - s1 ) & 0xffffL );
        *( rp ) = ( png_byte )( ( red >> 8 ) & 0xff );
        *( rp + 1 ) = ( png_byte )( red & 0xff );
        *( rp + 4 ) = ( png_byte )( ( blue >> 8 ) & 0xff );
        *( rp + 5 ) = ( png_byte )( blue & 0xff );
      }
    }
  }
}
#endif /* PNG_MNG_FEATURES_SUPPORTED */
#endif /* PNG_WRITE_SUPPORTED */
